—Deuteronomy 29:29 (NASB)
On the one hand, God has not revealed everything to us; on the other hand, He has revealed all that we need to know.
The problem experienced by many who engage in the pursuit to "fill in the blanks" of everything that God is going to do—either in the course of this life, the End Times, or eternity to come—is that it is often marked by disregard for what has already been revealed. The truly wise in God will "observe all the words of this law", seeking to obey what IS known even if it means forsaking the pursuit of what is not. I think this applies not just to issues of the future but to such things as how the universe was created and any of a myriad of "incomplete" subjects that can arrest our intellect. The correct biblical approach is to fill in the gaps with faith and obedience.
We should not be so eager to pursue the mysteries of God as to embrace what has already been revealed, because faith and obedience to what has already been given is all we need in order to be prepared for "the secret things".†††